Method and apparatus for mixing materials

ABSTRACT

Dry to pasty materials are mixed in a preferably cylindrical container with the aid of a mixing rotor which, like the container, has a horizontal axis and is eccentrically journaled in the container. The rotor cooperates with a mass-shifter device likewise rotatable about a horizontal axis for passing the material batchwise and intermittently to the mixing rotor. Each time, a portion of material located close to the peripheral wall of the container on one side of the rotor is moved by the massshifter device into the active mixing range of the rotor, the quantity of material thus mixed after each shifting action is piled up on top of the main heap of material located unilaterally in the container on the other side of the rotor.

States atent Sohn et al.

[ Mar. 14, 1972 [54] METHOD AND APPARATUS FOR MIXING MATERIALS Hermann Sohn KG Maschineniabrik, Dusseldorf, Germany 221 Filed: Sept. 28, 1970 211 Appl.No.: 75,885

[73] Assignee:

2,964,391 12/1960 Benson ..259/l04 Krahe ..259/6 Primary ExaminerRobert W. Jenkins AttorneyCurt M. Avery, Arthur E. Wilfond, Herbert L. Lerner and Daniel J. Tick [57] ABSTRACT Dry to pasty materials are mixed in a preferably cylindrical container with the aid of a mixing rotor which, like the container, has a horizontal axis and is eccentrically joumaled in the container. The rotor cooperates with a mass-shifter device likewise rotatable about a horizontal axis for passing the material batchwise and intermittently to the mixing rotor. Each time, a portion of material located close to the peripheral wall of the container on one side of the rotor is moved by the mass-shifter device into the active mixing range of the rotor, the quantity of material thus mixed after each shifting action is piled up on top of the main heap of material located unilaterally in the container on the other side of the rotor.

11 Claims, 4 Drawing Figures METHOD AND APPARATUS FOR MIXING MATERIALS Our invention relates to a method and to apparatus for mixing dry or pasty materials, for example powder of any kind, but is also suitable for chunky materials which are comminuted in the mixer and then, in pulverulent condition, are mixed with other solid or liquid substances.

Apparatus for mixing solid or liquid substances are known in a great variety of types. In a known design according to the German published Pat. application No. 1,239,549, the mixing material is located in a cylindrical mixing container and the mixing is effected with the aid ofa rotor whose axis is horizontal and eccentrically related to the container axis. The rotor cooperates with a mass-shifting device which forwards the material toward the rotor. The mixing container may perform a rotating or rocking emotion in such a manner that during each rotation of the container the mixing material is layerwise overturned. The mass-shifting device seizes each time a portion of the material and supplies it to the rapidly rotating rotor, the shifting device rotating either above the rotor axis or, in another embodiment of this mixer, above an axis parallel to that of the rotor. In the latter embodiment the action circle of the mass-shifting device extends tangentially to the action circle of the rotor. Although such mixers operates satisfactorily in general respects, they leave much to be desired because the supply of mixing material to the rotor is not properly controllable; that is, it may happen that in one and the same interval of time, the same quantity of material is repeatedly subjected to mixing by the rotor, whereas other quantity portions of the material enter less frequently into the action range of the rotor. By operating the mixer a correspondingly prolonged period of time, this deficiency can be moderated or obviated, a fact also applying to mixers of other types. The prolonged operation of the mixer, however, is uneconomical and in most cases also results in a higher increase in temperature of the mixing material.

It is an object of our invention, relating to a mixer generally of the above-mentioned type in which the mixing material is intermittently subjected to mixing treatment, to improve the efficiency and to also improve the product of the mixing process by subjecting the material more uniformly to the mixing treatment.

Another object of the invention is to reduce the increase in heat caused by the mixer operation in the material being mixed.

Still another object is to readily permit opening and cleaning the mixing apparatus from the easily accessible front thereof.

To achieve these objects, and in accordance with a feature of our invention, we subject a quantity of mixing material located near the container wall in individual shifts or batches to mixing treatment by the rotor and, after each shift, pile the just-mixed quantity of material on top of the main quantity located unilaterally of the rotor in the mixing container.

According to another feature of our invention, operating with mixing container having a horizontal axis and a rapidly rotating mixing rotor eccentrically journaled in the container and cooperating with a mass-shifter device slowly rotating about a likewise horizontal axis, it is preferable to give the mass-shifting device and the rotor a flying (unilateral) journal in a wall ofthe mixing container and to have the tool members of the mass-shifter device perform a circular travel about the rotor in eccentric relation thereto.

According to a further feature of the invention, the tools of the mass-shifter device have a travel path slightly and uniformly spaced from the peripheral wall of cylindrical mixing container so that the tools will seize the quantities of material that are unilaterally deposited directly adjacent to the container wall, thus supplying only these small quantity portions into the action range of the mixing rotor each time one of the tool members of the mass-shifter device acts upon the justmentioned portion of material. The space thus vacated by the quantity removed material is again filled by mixing material now gliding into that space, and the material mixed by the rotor is flung away therefrom and deposited on top ofthe main heap.

According to another feature of the invention, the distance of the rotor from the lowermost point of the mixing container or from the center plane passing vertically through the rotational axis of the mass-shifter device, is adjustable. This adjustment permits the penetrating depth of the rotor into the heap material and consequently the load imposed upon the rotor during the mixing process, to be always kept within satisfactory limits.

The above-mentioned and further objects, advantages and features of our invention, said features being set forth in the claims annexed hereto, will be apparent from the following description in conjunction with the embodiment ofa mixer according to the invention illustrated by way of example and the accompanying drawing in which:

FIG. l is a schematic and perspective view of a complete mixing apparatus;

FIG. la shows a detail of the same apparatus partly in section;

FIG. 2 illustrates schematically the same apparatus in two different positions of the mixing container; and

FIG. 3 is a rear view of the mixer shown in FIG. 1.

As illustrated in FIG. 1, the mixer has a cylindrical mixing container 1 fastened to a vertical supporting wall 2 mounted on a base 3 and laterally joined with further walls 4. The rear wall 5 of the mixing container may or may not be identical with the supporting wall 2. In the illustrated embodiment, a cover 6 structure placed upon the supporting wall 2 and the lateral walls t and has the shape of a funnel which opens into the mixing space 8 within the container 1, the funnel opening having the shape of a slot 9. The funnel serves to supply the material to be mixed. Rusher sheets or flaps 10 near the bottom of the mixing container serve to empty the mixing container. The front cover wall 11 is hinged to the mixing container as shown, or may be designed as a fully removable cover. The front cover 11 can be liquid-tightly joined with the mixing container with the aid of conventional elements, preferably rapid-clamping closures. The mixing rotor 12 is unilaterally journaled in the supporting wall 2, The rotor shaft 13 is supported in a bearing block 14 which is braced against the base plate 15. A clutch 16 connects the rotor shaft with a preferably speed-controllable drive motor 17. A mass-shifter or turn-over device 18, constituted essentially by a carrier plate 19 with laterally extending tool members or legs 20 is fastened to the end ofa shaft 21 which is also unilaterally journaled in the rear wall 5 of the drum-shaped container. As will be seen, the shaft 21 of the shifter device carries radially extended vanes 22 which aid in changing the level position of the mixing-material portions in the container.

As will be seen particularly from FIG. 1a, the turn-over tools 20 of the shifter device are preferably given the shape of flat strips and extend at an angle 0 to the radial plane 21 of the shaft 21 so that the mixing material gliding off the tools 20 enters into the action range of the rotor 12. As is further apparent from FIG. 2 the mixing material 23 is unilaterally heaped in the mixing space A during the mixing operation, the angle of repose a being dependent upon kind and particle size of the mixing material. If the mixing material is coarse, the angle of repose as a rule is larger than when the material has a smaller grain size. For mixing material permeated by liquid, the angle of repose is almost equal to zero.

The mass shifter, rotating during operation of the mixer, entrains the mixing good quantities 24 located near the peripheral wall of the container 1 and shifts these quantities into the action range of the mixing rotor 12 which rotates at higher speed than the mass-shifter, the rotational direction of the rotor being indicated by an arrow 25. The tool members 20 are angularly spaced apart from each other, and the speed of rotation is such that the rotor completes a mixing operation substantially during each interim of sequential tool actions.

The rotor flings the mixed quantity of material outward on top of the heap located in container 1 in front of the rotor. To secure the desired operation, the charge of material placed into the mixing container should occupy at most one-half of the container spacer 8.

If the mixing material charged into the container is changed, for example, if the charge is a powder to be mixed with a liquid, the repose angle a is nearly zero. In this case the rotor should also fully engage the mixing material and to fully develop its rated mixing power. For that reason the mixing container 1 is pivotally displaceable in such a manner that the rotor changes its distance from the bottom line 26 of the container 1. In the illustrated example, and as shown by broken lines, the mixing container is rotationally adjusted by the angle b so that the rotor is in the lowermost position relative to the mixing container. In the same embodiment the mixing container is angularly adjustable about the rotor axis 13, the angle amounting up to 30.

It will be seen from the rear view of FIG. 3 that the supporting wall 2 has a rather spacious recess 27 in which the flange bearing 28 for the mass-shifter shaft 21 is displaceable when the mixing container is being rotationally adjusted. A lifting mechanism 29, for example a hydraulically operated jack, is connected through a link 3 with a pin 31 fastened on the rear wall. The pin 31 extends through an oblong slot 32 of the supporting wall 2. The desired position of the rotor can also be changed during operation of the mixer by actuating a valve 33. A change in operating position of the rotor is desired when the load placed upon the rotor changes during the mixing process. It is a particular advantage of the illustrated apparatus that the mixing container, upon completion of the mixing job, can be readily cleaned by easily removing the front wall or cover 11. Furthermore, the illustrated design of the mixer does away with the bearings and particularly the sensitive bearing seals needed for rotational members passing through a wall, in the present case through the front wall, of the mixing container.

As apparent from the foregoing it is an essential feature of our invention that the mixing material, filling only a small amount of the container space, becomes predominantly heaped unilaterally in the container on one side of the rotor, and that only that portion of the material is supplied to the rotor which upon being mixed by the rotor has reached the opposite side, the material being flung away from the rapidly rotating rotor being piled up on the outside of the heap so that it forms the top layer of the heap on the other side of the rotor. Only some material from the bottom of the heap will then glide into the space vacated by a mass-shifter tool. By virtue of this process, the entire quantity of mixing material is continually and batchwise subjected to mixing in best feasible uniformity. As a result, the mixing process can be kept relatively short and the temperature of the material remains within satisfactory limits, as compared with the above-mentioned mixing machines heretofore available. The efficiency of the mixer is thus considerably increased. A variety of modifications can be applied to the illustrated mixer and within the scope of our invention. For example, the mixing container may also be turned about the axis of the mass-shifter device to thereby change the rotor positional adjustment relative to the lowermost line 26 of the container. Further, the mixing container may be equipped with a double jacket for heating or cooling the mixing material. Additional means may be provided for supplying the mixing material into the container such as pipes or other ducts for liquids, gases or powders. The rotor may be given a shape differing from the one illustrated, and the mass-shifter device may have a combshaped design and enter into meshing engagement with the mixing tools of the rotor.

To those skilled in the art it will be obvious upon a study of this disclosure that our invention permits of various other modifications and hence may be given embodiment other than those illustrated and described herein, without departing from the essential features of the invention and within the scope of the claims annexed hereto.

We claim:

1. The method of mixing dry to pasty material in a mixing container with a mixing rotor eccentrically rotatable in said container about a horizontal axis, and a mass shifter also rotatable in said container about a horizontal axis for batchwise passing the material to the rotor, which method comprises the steps of intermittently seizing a portion of the material from close to the container wall at one side of the rotor and shifting said portion into the mixing range of the rotor, and thereafter piling the just-mixed portion of material on top of a heap of material located on the other side of the rotor.

2. A mixing apparatus for dry to pasty materials, comprising a mixing container having a substantially horizontal axis when operative, a mixing rotor whose diameter is less than the inner width of said container and which is rotatable in said container about an axis parallel to and eccentrically spaced from said container axis, a mass-shifter device rotatable in said con tainer about an axis parallel to said container axis and radially spaced from said rotor axis, said device having mass-engageable tool members adjacent to the perimetric wall of said container, and said mixing rotor being situated in the action range of said members, whereby the material is batchwise moved from near said container wall on one side of said rotor into the mixing range of said rotor and thence onto the top of the heap of material located in said container on the other side of said rotor.

3. ln apparatus according to claim 2, said mass-shifter device having a rotational speed lower than that of said rotor, and said members of said mass-shifter device being peripherially spaced from each other for sequentially acting upon the material in time intervals individually sufficient for a mixing operation of said rotor.

4. In apparatus according to claim 3, said container having cylindrical shape, said rotor having a diameter smaller than the radius of said container and being located between the axis and the periphery of said cylindrical container.

5. In apparatus according to claim 4, said axis of said massshifter device being parallel to said container axis, and said members being movable on a circle passing between said rotor and the inner peripheral surface of said container.

6. In apparatus according to claim 2, said container being cylindrical and having a circular rear wall, said mass-shifter device and said rotor being unilaterally journaled in said rear wall.

7. In apparatus according to claim 6, said container having a front wall which forms an openable closure of said container.

8. In apparatus according to claim 2, said rotor being spaced an adjustable distance from the lowermost locality of said container, and said container being rotationally displaceable for adjusting said distance.

9. In apparatus according to claim 8, said container being rotationally adjustable about the rotor axis, and a lifting mechanism connected with said container for rotationally displacing it.

10. In apparatus according to claim 2, said mass-shifter device comprising a shaft and a carrier structure fastened to said shaft, said tool members being secured to said carrier structure, and vane members mounted on and radially extending from said shaft.

11. In apparatus according to claim 10, said tool members extending from said carrier structure in respective directions parallel to said mass-shifter axis and having respective faces angularly displaced relative to a radial plane of said latter axis.

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2. A mixing apparatus for dry to pasty materials, comprising a mixing container having a substantially horizontal axis when operative, a mixing rotor whose diameter is less than the inner width of said container and which is rotatable in said container about an axis parallel to and eccentrically spaced from said container axis, a mass-shifter device rotatable in said container about an axis parallel to said container axis and radially spaced from said rotor axis, said device having mass-engageable tool members adjacent to the perimetric wall of said container, and said mixing rotor being situated in the action range of said members, whereby the material is batchwise moved from near said container wall on one side of said rotor into the mixing range of said rotor and thence onto the top of the heap of material located in said container on the other side of said rotor.
 3. In apparatus according to claim 2, said mass-shifter device having a rotational speed lower than that of said rotor, and said members of said mass-shifter device being peripherially spaced from each other for sequentially acting upon the material in time intervals individually sufficient for a mixing operation of said rotor.
 4. In apparatus according to claim 3, said container having cylindrical shape, said rotor having a diameter smaller than the radius of said container and being located betWeen the axis and the periphery of said cylindrical container.
 5. In apparatus according to claim 4, said axis of said mass-shifter device being parallel to said container axis, and said members being movable on a circle passing between said rotor and the inner peripheral surface of said container.
 6. In apparatus according to claim 2, said container being cylindrical and having a circular rear wall, said mass-shifter device and said rotor being unilaterally journaled in said rear wall.
 7. In apparatus according to claim 6, said container having a front wall which forms an openable closure of said container.
 8. In apparatus according to claim 2, said rotor being spaced an adjustable distance from the lowermost locality of said container, and said container being rotationally displaceable for adjusting said distance.
 9. In apparatus according to claim 8, said container being rotationally adjustable about the rotor axis, and a lifting mechanism connected with said container for rotationally displacing it.
 10. In apparatus according to claim 2, said mass-shifter device comprising a shaft and a carrier structure fastened to said shaft, said tool members being secured to said carrier structure, and vane members mounted on and radially extending from said shaft.
 11. In apparatus according to claim 10, said tool members extending from said carrier structure in respective directions parallel to said mass-shifter axis and having respective faces angularly displaced relative to a radial plane of said latter axis. 